This invention relates to the field of stick placer apparatus and, in particular, to spacing stick depositing mechanisms.
Spacing stick placer apparatus are used to place spacing sticks between stacked tiers of green lumber. The sticks serve to provide space between the tiers of lumber to allow air flow for either kiln drying or air drying, as well as to stabilize the tiered lumber package. Typically, spacing stick placer apparatus are used in conjunction with lumber stackers that stack the green lumber in tiers, the stick placer apparatus conventionally being placed over the lumber stacker. The sticks are placed in spaced parallel array across the width of the lumber tiers, the sticks aligned perpendicular to the long dimension of the lumber. The number of sticks so placed depends upon the length of the lumber and the desired spacing between the sticks. In modern sawmill practices it is desired that the first and last stick of the array of sticks placed onto a tier of lumber be placed flush with the ends of the lumber.
It is conventional for sticks to be conveyed over the lumber stack from a stick allocating device by means of a continuous chain, for example a lugged chain. The lugs on the chain are translated past a stick allocating device. A pair of continuous chains co-operate with the stick allocating device so that opposed pairs of lugs receive single sticks from the stick allocating device and convey those sticks along the continuous chain over the lumber stack. The chains move linearly along an opposed pair of tracks supported above the lumber stack, the tracks supported conventionally by a support frame. The continuous chains are supported at either end of the opposed pair of tracks by sprockets, one of which is conventionally a drive sprocket, the other an idler sprocket.
As observed by Rysti in the U.S. Pat. No. 3,823,834, prior art includes several methods and devices for performing the insertion of piling strips in timber packages, but in all these methods and devices drawbacks have been observed, which above all are associated with the feeding of piling strips, whereby the operation of feeding piling strips has become the main factor restricting the capacity of piling strip insertion machines. In devices belonging to prior art, the feeding of piling strips is most commonly accomplished as follows: most commonly used is the method in which the piling strips are stacked in magazines, of which as many have been provided side by side as is the number of piling strips needed between the timber courses in each instance. When one timber course has been completed, the piling strips are caused to fall down on the course either by pushing them from the side, by pushing them from the end or by releasing them at the ends. Prior art also includes a method and devices wherein the piling strips are conveyed into positions above the timber course by means of an endless conveyor, from which the piling strips are caused to fall down or released to be deposited upon the completed course. A drawback encountered in those devices in which the piling strips are caused to fall down on the timber course is the bouncing of the strips, whereby they fail to be deposited in their correct positions and for example may end up lying on their side edges so that, because they are rectangular, the laying of the next tier is uneven. Disturbance of the intended piling strip distribution, again, may cause twisting and warping of the timber, and non-uniform drying. In addition to the problem of bowed or crooked sticks, the surface of a lumber stack is rarely completely level, given that each piece of lumber is usually not exactly the same shape as the adjacent piece or each may be warped, spacing sticks which are dropped or not positively placed increase the likelihood of the stick being bounced and misplaced.
Consequently it is an object of the present invention to provide a device for the positive placement of spacing sticks onto a stack of lumber. In this regard applicant is aware of U.S. Pat. No. 4,801,233 which issued to Ritola on Jan. 31, 1989 for a xe2x80x9cSticker Placer Apparatusxe2x80x9d which teaches a device for the positive placement of spacing sticks onto a stack of lumber. Sticks are fed from a stick conveyor into inclined stick feeding pockets, the stick feeding pockets indexing individual sticks into the grip of actuable stick supporting and pinching arms rotatably mounted at the lowermost end of vertically translatable placement plungers. The vertical position of the placement plungers, and thus the position of the stick supporting and pinching arms, is governed in the Ritola device by an actuating arm releasing or increasing the tension on a flexible chain extending between the stick supporting and pinching arms and the actuating arm. Positive placement of a stick from the supporting and pinching arms is accomplished when the lowermost end of the vertically translatable placement plunger engages the top surface of a stack of lumber. Continuing detensioning of the flexible chain by the actuating arm allows the rotatably mounted stick support arm to rotate under the return biasing force of a resilient spring so as to deposit the stick from the support arm onto the stack of lumber.
The stick placer of the present invention includes a stick magazine and a stick receiver. The magazine may be mountable into cooperation with a stick diverter on a stick conveyor so as to divert sticks from the stick conveyor into the magazines. The magazine is for holding sticks in a generally planar mat so as to bias a lowermost stick in the mat against a selectively removable stop. The stop regulates passage of the lowermost stick from a lower opening in the stick magazine.
The stick receiver is rotatable and has a stick receiving pocket. The stick receiver is selectively rotatably mounted adjacent the lower opening in the stick magazine. The stick receiver is rotatable between a stick receiving position and a stick depositing position. In the stick receiving position the pocket cooperates with the lower opening so as to receive the lowermost stick into the pocket when the stop is selectively removed so as to release the lowermost stick from the lower opening in the magazine. In the stick depositing position, the stick receiver is angularly displaced from the stick receiving position so as to dispose the pocket for deposit of the stick from the pocket onto an upper tier of a stack of lumber.
The stick receiver has a cam surface above the pocket for engaging the lowermost stick when the lowermost stick is not in flush engagement with the upper tier of the stack of lumber upon deposit from the pocket, for example when the upper tier is uneven or the stick is bent or bowed or lying side-on.
The stick receiver may have a rounded lower surface defining a lower fork beneath the pocket. The lower fork may be thinner than a gap dimension of the pocket corresponding to a thickness of the sticks.
The stick magazine may be inclined and the mat may be a mat of the sticks laid flat so as to abut adjacent side surfaces of the sticks.
The pocket may be a generally rectangular channel in the stick receiver, the pocket sized to receive entirely within the pocket a lateral cross-section of the lowermost stick. The stick receiver may rotate generally 90 degrees between the stick receiving position and the stick depositing position. When in the stick depositing position, the pocket may be downwardly inclined. The cam may be adjacent the pocket. The pocket and a lower surface of the stick receiver may define a fork therebetween. The lowermost stick is supported on the fork when in the pocket. The cam may be a rigid projection, generally parallel to the fork, forming an upper edge of the pocket. The cam may have a rounded cam surface at a distal end of the projection. The rigid projection and the fork may be located on a common side of the stick receiver relative to an axis of rotation of the stick receiver.
The stick receiver may be at least one disc or may include a pair of discs mountable onto a shaft for rotation about a longitudinal axis of the shaft.
The shaft may be parallel to the lower opening of the magazine. The stop may be a lever arm pivotally mounted to the magazine and selectively pivotable by a selective actuator so as to urge an end of the lever arm between a closed position clamping the lowermost stick in the lower opening of the magazine, and an open position releasing the lowermost stick from the lower opening.
The fork may have a rounded under-surface, rounded according to a radius of curvature of the stick receiver about axes of rotation of the pair of discs. The pair of discs may have a common axis of rotation.
A rigid member may be mounted relative to the stick receiver so that as the pocket is rotated from the stick receiving position to the stick depositing position, a stick held in the pocket engages the rigid member so as to be urged by the rigid member from the pocket.
The stick receiver may be selectively positionable by a vertical positioning actuator between elevated and lowered positions. In the elevated position the stick receiver is adjacent the lower opening in the magazine and the pocket is in the stick receiving position. In the lowered position the stick receiver is adjacent the upper tier and the pocket is in the stick depositing position.